Boeing SAM-A-1GAPA

In June 1946, the U.S. Army Air Force began project MX-606, and awarded Boeing a contract to study the general problems
involved in the development of a surface-to-air guided missile (briefly designated as JB-8).
The project was labeled GAPA (Ground-to-Air Pilotless Aircraft),
and in late 1945, MX-606 was extended to cover the development of a tactical supersonic surface-to-air missile. In 1947, the designation
SAM-A-1 was assigned to GAPA, and between 1946 and August 1950, more than 100 XSAM-A-1GAPA test missiles were
launched.

Photo: Boeing

XSAM-A-1 (Boeing Model 602)

The XSAM-A-1 vehicles were of several significantly different configurations to test various aspects of the projected operational
missile. The first missiles, Boeing Model 600 series, were two-stage solid-propellant rockets of various configurations, and were used
for basic aerodynamic research. The first Model 600 launch occurred in January 1946, but the first stable flight did not succeed before
July that year. The Model 601 series, first launched in March 1948, had a solid-fueled booster, a liquid-propellant rocket sustainer,
and was used to test the GAPA's guidance system. The latter consisted of radar beam-riding mid-course guidance and, in some variants,
a target seeker for terminal homing. The Model 602 series was boosted by a solid-fueled rocket and tested ramjets as cruise propulsion
system. It was first launched in November 1947. Under the Model 603 designator, many different configurations for the tactical missile
were studied, but none were actually built. In general, the operational SAM-A-1 would have used a ramjet sustainer, beam-riding guidance,
and some sort of terminal homing system.

Photo: via Gatland

XSAM-A-1 (Boeing Model 601)

The GAPA tactical missile program was terminated in 1949, when the USAF's surface-to-air missile development had turned toward
the much larger and more advanced IM-99/CIM-10 Bomarc.

Specifications

Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!